People's attitudes toward the planet and other people. In this ideal world, we have eradicated needless hate. It's unnecessary, and doesn't benefit anyone. In this ideal world, we also have perfected reverse combustion. To fuel our cities, we are now splitting carbon dioxide into carbon and oxygen. So now we are purifying the air while we are powering stuff. Commercial farms are now built up versus taking up large swaths of vertical land. These farms are actually more efficient since you can control the temperature, they won't suffer from weather conditions either. This much change would probably have to be the result of some form of revolution unfortunately.

I remember the scythe series really resonating. It was about sort of an ex-utopia. Starts out as a future civilization with a benevolent robot as the controller of the world, but eventually, rather than the robot try to take over the world, the people dedicated to curbing overpopulation, start murdering people to gain control of society, and the robot who actually loves people, can't do anything to stop them. In this society, for the most part it's euphoric, until this happens.

Image: _ashlee_ - Attribution 2.0 Generic (CC BY 2.0)